1. Field of the Invention
The present invention relates to a battery pack having a battery stack and a fan for supplying and exhausting a medium of the battery stack, and to the configuration of a duct for supplying and exhausting the medium of the battery stack.
2. Description of the Related Art
Heretofore, electric vehicles, hybrid electric vehicles, and fuel cell vehicles were equipped with a battery pack for storing electric power to supply a drive motor.
The battery pack includes a cooling fan for taking in cooling air from the outside for cooling the battery stack configured by combining multiple battery modules.
The battery pack has an upper case for covering the upper part of the battery stack and a lower case for covering the lower part. Built into the battery pack is a battery stack having battery modules formed from one or multiple cells, such as nickel-metal hydride battery or lithium ion battery, having cooling passages located between them in parallel, assembled by binding between end members located at both ends, and having the battery modules electrically connected in series.
FIG. 5 shows an internal configuration of a battery pack 100 of the prior art with its upper case detached. A cooling fan 30 is arranged in line with one end in the longitudinal direction (x direction) of the battery pack 100 within the battery pack 100. Furthermore, a junction duct 200, fabricated from blow-molded plastic, for example, for taking in cooling air from a chamber space formed between the upper part of the battery stack and the upper case is provided on the upper part of a fan opening 32 formed on the top surface of the cooling fan 30.
FIG. 6A is an external perspective view of the junction duct 200. Furthermore, FIG. 6B shows a cross section of the junction duct 200 as viewed from the direction of the arrow along line A-A of FIG. 6A. FIG. 6C shows a cross section of the junction duct 200 as viewed from the direction of the arrow along the line B-B of FIG. 6A. As shown in FIGS. 6B and 6C, two vertical supports 202a, 202b, for example, are formed within the junction duct 200 as reinforcing members preventing deformation of the junction duct 200.
Furthermore, Japanese Patent Laid-Open Publication No. 2001-354039 discloses a battery pack having a blower fan, for taking in cooling air, provided on the outside of a battery case for housing battery cells.
Moreover, Japanese Patent Laid-Open Publication No. 2002-219949 of FIG. 3 discloses a battery pack having a blower fan, for taking in cooling air, provided on the outside of a battery case for housing battery cells. Furthermore, Japanese Patent Laid-Open Publication No. 2002-219949 discloses a configuration where part of an exhaust duct forms a wall of an upper case.
Since the fan opening 32 of the cooling fan 30 and the junction duct 200 are adjacent when the junction duct 200 is provided on the upper part of the fan opening 32 of the cooling fan 30 as described hereinabove, the turbulence from the cooling air generated by rotationally driving the cooling fan 30 reaches the vertical supports 202a, 202b provided inside the junction duct 200 causing the vertical supports 202a, 202b as well as the entire junction duct to vibrate and may generate noise. Furthermore, since the vertical supports 202a, 202b are in the path of the cooling air taken into the cooling fan 30 and obstruct the path of the cooling air, turbulence may occur in the cooling air at the vertical supports 202a, 202b causing the vertical supports 202a, 202b as well as the entire junction duct to vibrate and may generate noise.